Overdrive control system



Dec. 29, 1942. E. M. CLAYTOR 2,306,865

' OVERDRIVE CONTROL SYSTEM Filed Dec. 9, 1940 To mam/Burch INVENTOR m5 M I I ATTORNEYd/ Patented Dec. 29, 1942 OVERDRIVE CONTROL SYSTEM Edward M. Glaytor, Anderson, General Motors Corporation, corporation of Delaware Ind., assignor to Detroit, Mich., a

Application December 9, 1940, Serial No. 369,246

4 Claims.

This invention relates to electrical control systems for automobile overdrives and, particularly to the type of overdrive control system in which the engine ignition is rendered inoperative for the purpose of facilitating retraction of the sun gear locking pawl from the sun gear locking ring, and in which the ignition is rendered operative again in response to the retraction of the pawl. In this type of system the pawl is usually retracted immediately following the rendering of the ignition inoperative. However, if the pawl should fail to come out the ignition will remain inoperative under certain driving conditions.

It is an object of the present invention to automatically restore the ignition in response to deceleration of the car to a predetermined low speed so that the engine will be operative to propel the car at least at low speed. This will give the car driver an opportunity to accelerate again to a speed at which the ignition becomes inoperative and give the pawl a second opportunity to come out when the ignition is interrupted. In any event, the driver will have means of transportation to a service garage.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein preferred embodiments of the present invention is clearly shown.

In the drawing:

Fig. 1 is a wiring diagram of an overdrive control system embodying the present invention applied to the type of overdrive in which the pawl is spring urged into engagement with the sun gear locking ring and in which the solenoid operates to retract the paw In this system the ignition is rendered inoperative by grounding the ignition apparatus between the coil and the timer.

Fig. 2 is a wiring diagram of a control system applied to. the same type of overdrive as indicated in Fig. 1. the system in Fig. 2 being one in which the ignition apparatus is disconnected from the current source in order to render it inoperative.

Fig. 3 is a wiring diagram of a control system applied to the type of overdrive in which a solenoid causes the pawl to engage the sun gear locking ring and in which a spring retracts the sun gear. dered inoperative by grounding the ignition circuit between the coil and the timer.

Referring to Fig. 1, 23 designates the overdrive solenoid. Solenoid 2|] comprises an armature 2| surrounded by an attracting coil 22 and a hold- In this system the ignition is rene ing coil 23. Armature 2| is connected. with a rod 24 the lower end of which is connected with a pawl 25 urged by spring 26 into engagement with a sun gear locking ring 21. The upper end of rod 24 is adapted to engage a resilient contact arm 28 carrying a contact 29 for engaging a contact 30 to connect the attracting coil 22 with ground. When coils 22 and 23 are energized the armature 2| moves upwardly, provided the ignition is interrupted, and the upper end of rod 24 engages support 28 to separate contact 29 from contact 30 thereby opening the circuit of the main attracting coil 22 thus leaving holding coil 23 operating to maintain the armature 2| in operative position.

The solenoid 20 controls a switch for grounding the ignition until the pawl 25 is retracted. This switch comprises a resilient contact support 3| carrying a contact 32 for engaging a contact 33. Support 3| carries an armature 34 which, when the coils of solenoid 20 are en ergized, moves downwardly to close contacts 32 and 33. The closing of contacts 32 and 33 will ground the ignition in the manner to be described. The ignition being interrupted, pressure between the sun gear locking ring 21 and the pawl 25 will be interrupted thereby facilitating the retraction of the pawl 25. During this retraction a collar on rod 24 engages armature 34 and causes the same to move upwardly to separate contact 32 from contact 33. ignition ground is broken and ignition is resumed.

The ignition appartus comprises a coil 40 having a primary winding 4| and a secondary winding 42 connected respectively with a timer 43 and with a distributor not shown. Primary winding 4| is connected by switch 44 with battery 45. From a point 46 between the coil 40 and the timer 43 a wire 41 leads to a contact 52 of an air vane switch 50. Switch 5|! comprises an air vane 5| carrying contact 53 for making engagement with the contact 52. Vane 5| is pivoted at 54 and is connected by wire 55 with contact 33. A spring 56 urges the vane 5| into normal position against a stop 51. At a certain predetermined car speed the vane 5| moves counterclockwise under the action of an air current represented by arrow 58 caused to impinge upon the vane 5| by the engine cooling fan 59. The car speed at which switch 5|] closes corresponds to the speed at which the overdrive becomes operative. In the type of overdrive represented at Fig. l, the going in to overdrive is effected by means of a centrifugal clutch. If, for

Then the v example this clutch is designed to cause the transmission to go into overdrive at 30 M. P. 1-1., the switch 50 should be constructed so as to close at a somewhat lower speed, for example 25 M. P. H. Therefore, by the time this clutch operates the switch 50 will have been closed.

When it is desired to come out of overdrive in the hgher speed range, it is necessary to connect the solenoid windings with the battery 45. This is accomplished by energizing the coil SI of a relay switch 50 having normally open contacts 62 and 63 for connecting the battery 45 with a wire 64 lead ng to a common terminal 65 to which the coils 22 and 23 of the solenoid are connected. The circuit of the coil 6| of relay 6!! is controlled by a driver operated kick switch '50 having stationary contacts II and I2 normally unbridged by movable contact 13 urged by a spring '54 against a stop I5. When the driver presses the switch rod I6 downwardly to close the switch 70 the battery 45 will be connected with the coil 6! and the contacts 62 and 53 will be closed thus completing a circuit between the battery 45 and the windings of solenoid 20. Then the armature 2I will be attracted upwardly and the armature 34 downwardly. Contacts 52-53 and contacts 32-33 then being closed, the ignition will be grounded to render the engine inoperative and thus relieve the pressure between the pawl 25 and sun gear locking ring 2'! and thereby facilitating the retraction of the pawl 25. The upward movement of the rod 24 causes the switch contacts 32 and 33 to be separated thereby restoring the ignition after the pawl 25 has been retracted.

If, for any reason the pawl should fail to be retracted altho the ignition be rendered inoperative, ignition will be restored automatically when the vehicle deoelerates to a predetermined lower speed at which the switch 50 will open thereby interrupting the ignition ground circuit. The switch 50 may be constructed to open at 15 M. P. H. so that the engine will be operative to propel the vehicle speeds up to the closing speed of switch 50, which is 25 M. P. 1-1. This will give the driver an opportunity either to drive to a service garage or to attempt to take the transmission out'of overdrive by attempting to accelerate the car above 25 M. P. H., whereupon the switch 50 will close and perhaps the pawl 25 will be retracted during the second period of ignition interruption. At any rate the driver will be able to drive the car at speeds below 25 M. P. H altho the transmission may remain in overdrive.

In the system shown in Fig. 2 an ignition circuit interrupting relay 80 is employed. Relay 8% comprises a magnet coil BI connected between the battery 45 and contact 62 of relay switch 60. Ignition interrupting relay 80 provides contacts 82 and 83 for connecting battery 45 with ignition switch 44 which is connected with the ignition apparatus. The contacts 52 and 53 of air vane switch 50, when closed, provide a by-pass around contacts 32 and 83.

The type of overdrive with which the system shown in Fig. 2 is used is the same type as that with which the system shown in Fig. 1 is used. This type is one in which the overdrive is effected automatically in response to the operation of a centrifugal clutch. The switch 50 (of Fig. 2) is set to open at a speed somewhat below the speed to which this clutch become operative. When it is desired to come out of overdrive the switch 50 will be open and the by-pass around contacts 82 and 83 of relay 80 will be interrupted. To come out of overdrive when using the system of Fig. 2, the operator closes switch whereupon relay 50 closes and connects the battery with the windings of solenoid 20 and with the winding SI of relay 3% Since the attracting coil 22 of solenoid 20 is one having relatively low resistance the current flow thru 8| will be relatively high and will be sufficient to cause contacts 82 and 83 to open thereby disabling the ignition by disconnecting the ignition apparatus from the battery Normally the pawl 25 will be retracted and the contact 22 will be separated from the contact as in the case of Fig. 1, thus rendering the holding coil 23 operative to maintain the pawl 25 in retracted position. The open circuiting of the magnet coil 22 considerably reduces the curr nt flow from the battery through the coil 23 of relay 22; and relay closes to restore the ignition. Obviously the restoration of the ignition depends on the separation of contact 29 from contact 3i; and that separation depends on retraction of the pawl 25. If, for some reason the pawl 25 be not retracted altho solenoid 20 is energized, heretofore it would be necessary to partially close the throttle to reestablish ignition. however, I provide the switch 50 which, like the switch of Fig. 1 Will close at 15 M. P. H. for example, to restore the ignition at a lower car speed regardless of failure of the pawl to be retracted from the sun gear, and regardless of throttle position.

The system. shown in Fig. 3 is one which is applied to the type of overdrive in which the pawl is urged electromagnetically into locking engagement with the sun gear locking ring and is retracted by a spring. In Fig. 3 the pawl is blocked from engagement with the sun gear looking ring by blocker plate 92 which releases the pawl 90 at a time when there is reversal of torque between the engine and transmission. Pawl 90 is connected with a pawl rod 93 which extends thru the stationary core 94 and the movable armature 05 of the overdrive solenoid designated by numeral I00. Armature 95 and core 04 are surrounded by the solenoid windings comprising an attracting coil 36 and a holding coil 97. Coil 2% is connected with ground to the battery thru contacts 88 and 09, the latter being mounted on a resilient grounded support IOI and having an end located in the path of the movement of the flange of a nut H12 fastened to the armature 95. The armature $5 is held in the upper position by a spring its urging the nut I02 against a stop Hit. Downward movement from the armature 95 to the rod 92 is transmitted thru a spring I05 located between the nut I02 and a shoulder I05 in rod 93. The solenoid controls an ignition. grounding switch comprising contacts I07 and 508, the latter being connected with a resilient support I be which is actuated by the rod 03. When the rod 23 moves downwardly to cause the pawl 90 to engage the sun gear locking ring 9| the contacts itll' and I08 will be closed.

The solenoid control relay 60 of Fig. 3 includes a pair of normally closed contacts H0 and III. Contact I It is connected by wire II2 with a point N3 of the ignition circuit between coil 30 and timer 43. Contact II I is connected with a con-- tact lit adapted to engage a contact II5 insulatingly supported by an air vane IIS grounded at I l! and forming a part of air vane switch I20. Contact H5 is connected by wire N50. with re-- silient contact blade I00 of solenoid unit I00.

Vane H6 is normally urged by a spring H8 against a stop H9. Vane H6 carries a contact I2I for engaging a resiliently supported contact I22 connected by wire 123 between gear switch I25 and kick switch I39. The circuit of coil SI of relay cs is controlled by series connected gear switch 25, kick switch 130 and a governor switch I35.

1 Switch I25 comprises stationary contacts I26 and I2! normally unbridged by contact I28 urged upwardly by spring i293. Switch I25 is closed automatically when the regular automobile transmission is in intermediate or high condition.

Kick switch I36 comprises stationary contacts I3! and i22 normally bridged by contact I33 urged upwardly by a spring i3 5. The switch operating rod i330. is located in the path of the movement of the accelerator pedal and is so related to it that the downward movement of the accelerator pedal is required for quick acceleration will open the switch I30.

Governor switch 135 comprises stationary contacts 36 and i3? normally unbridged by contact 533 urged upwardly by spring I32. responsive device not shown this switch is caused to close at 30 M. P. H. This speed responsive device may be in the form of an air vane or may be one which is operated by rotating shaft connected the vehicle transmission. If, for example, a governor switch I35 is constructed to close at 30 M. P. H. then the air switch i122 will be constructed to close contacts H t-4E5 at a somewhat lower speed, for example 25 M. P. 1- Switch tacts at a lower speed, for example, 15 M. P. H. Switch I22 is constructed so as to close contacts i2I and I22 at a speed in the higher driving range such as 55 M. P. H.

The operation of the system shown in Fig. 3 is as follows: The car being in second or high gear switch I25 will be closed. When the car speed attains 30 M. P. 1-1., for example, the switch 535 will close. Relay coil 5| will then be connected with the battery so and contacts 62 and 53 will close to connect the solenoid windings 96 and 91 with the battery 45; and contact H and I I I will open so as to provide a gap in the ignition ground-out line. The driver then releases the accelerator pedal to allow the engine speed to fall a certain percentage below equivalent car speed thereby causing a reversal of torque between the engine and transmission thereby cans ing the blocker plate 92 to release the pawl 99 thereby permitting the spring IE (compressed by'the downward movement of the armature 95) to move the pawl into engagement with the looking ring oi. Then the transmission is in overdrive.

When it is desired the driver will move the accelerator pedal downwardly sufficiently for quick acceleration thereby opening switch I30 and deenergizing relay 62. Then the contacts 52 and (53 will open to disengage solenoid I86 and contacts H2 and iII will close to complete a short circuit of the ignition apparatus which includes the following: point H3 in the line between coil to and timer wire H2 contacts H0 and HI of relay Gil, contacts IE4 and H5 of air switch l29 and contacts Iiii and H38 of solenoid unit Hit. The ignition grounding circuit being then completed, the engine is non-operative and the pressure between the pawl 98 and the locking ring oi is relieved, thereby permitting the spring I33 to move By a speed I28 will be constructed to open these conto pass a car on the road,

the pawl'llii u ward. By the time the pawl 9i) 7 has been fully retracted, the contacts I88 and IE]? will be separated thereby interrupting the ignition ground and restoring the ignition. If, however, the pawl should fail to be retracted, ignition would not be restored were it not for the presence of the switch E22 which provides for the opening of the ignition ground by theseparation of contacts H4 and H5 which takes place at a speed of 15 M. P. H.

Therefore the engine will propel the vehicle at speeds up to just below 25 M. P. H. altho the transmission remains in overdrive.

The switch I29 of Fig. 3 has the additional feature of providing for the by-pasing of switches E30 and I at speeds in the higher range (55 M. P. H. for example) by closing contacts PM and I22 so that the transmission can not be taken out of overdrive in the higher speed range.

From the foregoing description of three embodiments of the present invention it is apparent that I have provided in combination with means for interrupting ignition when it is desired to come out of overdrive, means for restoring ignition in response to coming out of overdrive, a means responsive to deceleration of the car to a predetermined lower speed for restoring the ignition in any event regardless of failure of the pawl to release the sun gear locking ring.

It will be understood that the illustration of switches [55 and I22 is purely diagrammatic and that various well known spring toggle connections may be employed to obtain the desired speed differential between the closing and opening of contacts 52 and 53 of switch or between the closing and opening of the contacts H2 and H5 of switch I20.

While the embodiments of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An overdrive control system for controlling the sun gear locking pawl of an overdrive transmission, said system comprising a solenoid for controlling the pawl, means for controlling the solenoid, and engine ignition controlling means having provisions for rendering the ignition inoperative in response to conditioning the solenoid for taking the transmission out of overdrive, having provisions for restoring the ignition in response to retraction of the pawl for the sun gear, and having speed responsive provisions for restoring the ignition at a car speed less than the speed at which the transmission goes into overdrive, said last-mentioned provisions being operative regardless of failure to retract the sun gear locking pawl.

2. An overdrive control system for controlling the sun gear locking pawl of an overdrive transmission, said system comprising a solenoid for controlling the pawl, means for controlling the solenoid, an ignition grounding circuit for rendering the ignition inoperative and comprising a normally open switch closed in response to conditioning the solenoid for taking the transmission out of overdrive and opened in response to retraction of the sun gear locking pawl, and a normally open switch closed in response to a certain car speed corresponding approximately to the speed at which transmission goes into overdrive, but opening in response to deceleration to a lower speed.

3. An overdrive control system for controlling the sun gear locking pawl of an overdrive transmission, said system comprising a solenoid for controlling the pawl, means for controlling the solenoid, an ignition circuit interrupting relay having its magnet coil fully energized at the time the solenoid is conditioned for taking the transmission out of overdrive whereby the ignition controlling contacts of said relay open to disconnect the current source from the ignition, means responsive to retraction of the pawl for causing said relay to close the ignition interrupting contacts, and means responsive to deceleration of the car to a speed less than that at which going into overdrive takes place for establishing an ignition circuit regardless of failure to retract the sun gear locking pawl.

4. An overdrive control system for controlling the sun gear locking pawl of an overdrive transmission, said system comprising a solenoid for controlling the pawl, an ignition grounding circuit comprising normally closed contacts opened in response to energization of the solenoid to go into overdrive, a pair of normally opened contacts closed in response to a car speed corresponding to the speed at which the transmission goes into overdrive and opened in response to deceleration to a speed less than the lower limit of the normal range of overdrive speed, and a pair of normally open contacts closed when the pawl locks the sun gear and opened when the pawl is retracted, a solenoid control relay for controlling the first mentioned contacts of the ignition grounding circuit, and a speed responsive means for controlling the second-mentioned contacts of the ignition grounding circuit said means being set to close at a speed substantially higher than the opening speed.

EDWARD M. CLAYTOR. 

